1. Field of the Invention
The present invention relates to an auto-focus method for camera, and particularly to a method of obtaining a focal position automatically utilizing an only single image.
2. Description of Related Art
With development in the technology and extensive use of digital devices, the relationship forged between people and digital products has become increasingly closer. Among the digital products, the digital camera (DC) has occupied a rather important share. To determine whether a digital camera is good or bad, besides the imaging quality, the focusing technique of the digital camera also needs to be taken into consideration. Focusing in a digital camera has to be conducted not only fast, but also accurately. The speed and effect of focusing would directly affect the speed and quality of imaging in the digital camera.
As far as the current focusing technique is concerned, completion of the focusing in a camera is determined by a feature function. FIG. 1 is a schematic view illustrating a conventional focusing process in a camera. Referring to FIG. 1, during the focusing process in a camera, pictures need to be taken at a plurality of focal points respectively to estimate or determine a position of an optimal focal point. Therefore, the captured picture needs to undergo a process of “blur-clearness-blur-clearness resumed”. The process of searching for the focal point is rather time-consuming. Moreover, focusing conducted in this method does not comply with consumers' natural habits, and the method also requires photographing at a plurality of focal points and thereby increasing the power consumption of the digital camera. However, today's consumers not only pursue the quality of photographs taken by a camera, but also value the sustainability of batteries in the camera. Therefore, if focusing is conducted in a more power-saving method, the sustainability of the batteries in the camera can be significantly increased.
In consideration of the aforementioned, relevant manufacturers of cameras all seek after suitable solutions to solve the said problem.